Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.6.4 (chondroitinase)
 2,039 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The distribution of hyaluronic acid in the oocyte-cumulus complexes collected from the oviduct ampulla of superovulated hamsters was revealed by use of hyaluronidase coupled to colloidal gold. On thin sections of Lowicryl-embedded oocyte-cumulus complexes, gold particles were associated specifically with interconnecting fibrillar materials that make up the cumulus matrix. Inside the cumulus cells, gold particles were found over the cisternal membrane of the rough endoplasmic reticulum, in the contents of lysosomes and multivesicular bodies, and over Golgi vesicles of some cumulus cells. A high concentration of gold labeling was observed over the peripheral condensed chromatin and perinucleolar components in the nucleus. The cell surface of the cumulus cells also appeared to be labeled. Gold particles, however, were absent over the mitochondria and lipid vacuoles. In the oocytes, labeling was found to be associated mainly with rough endoplasmic reticulum and arrays of lamellar structures; cortical granules, mitochondria, and coated vesicles were essentially devoid of gold particles. Gold particles were also seen along the plasma membrane of the oocytes and within the perivitelline space. The zona pellucida was not labeled by hyaluronidase-gold. Different control experiments confirmed the specificity of the labeling. Digestion of thin sections with hyaluronidase prior to incubation with hyaluronidase-gold abolished the initial reaction, whereas treatment of thin sections with chondroitinase did not prevent labeling of oocyte-cumulus complexes by hyaluronidase-gold. Although the function of hyaluronic acid in the oocyte-cumulus complex at the time of ovulation and fertilization is not known, the high concentration of this particular compound in the cumulus matrix and the cumulus cells and its specific locations in the perivitelline space and in the superovulated oocytes implicate the significance of its presence and warrant future investigations.
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PMID:High-resolution localization of hyaluronic acid in the golden hamster oocyte-cumulus complex by use of a hyaluronidase-gold complex. 228 56

In order to study the temporal and topological events involved in the processing and assembly of chondroitin sulfate proteoglycan, a fractionation scheme involving differential centrifugation and discontinuous sucrose density gradient centrifugation was developed for homogenates of chick embryo sternal chondrocytes. The precursors in these subcellular fractions were examined by a series of pulse, pulse-chase, and continuous labeling experiments. When chondrocytes were pulsed for 20 min with [35S]methionine, an immunoprecipitable core protein precursor with an approximate molecular size of 376,000 Da was localized to the rough endoplasmic reticulum fractions. Further incubation under chase conditions showed the presence of the 376,000-Da species as well as two additional polypeptides of higher molecular masses in the smooth membrane-enriched fractions within the next 2 h. This translocation did not occur in the presence of the energy transfer inhibitor carbonyl cyanide-m-chlorophenylhydrazone. The labeling pattern of the newly synthesized core protein precursor with either [3H] mannose or [3H]glucosamine showed that N-linked oligosaccharide addition was found on the earliest synthesized product in the rough endoplasmic reticulum, and the addition of this oligosaccharide was inhibited by co-incubation with tunicamycin. Furthermore, the high mannose oligosaccharide was susceptible to cleavage by endo-beta-N-acetylglucosaminidase H, while upon chase approximately 56 and 31% of the glucosamine- and mannose-labeled oligosaccharides, respectively, were processed to resistant forms, presumably in the Golgi complex. Both direct assay of glycosyl- and sulfotransferases requisite for addition of chondroitin sulfate chains and sensitivity of intracellular precursors to chondroitinase, keratanase , and endoglycosidase H suggest that only the N-linked oligosaccharides are added in the rough endoplasmic reticulum and glycosaminoglycan chain addition occurs predominantly in smooth membranes.
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PMID:Subcellular localization of the synthesis and glycosylation of chondroitin sulfate proteoglycan core protein. 672 88

Detailed studies of the effects of the ionophore monensin upon avian chondrocyte ultrastructure, macromolecular synthesis, and macromolecular secretion have been carried out. Embryonic avian chondrocytes in suspension culture were incubated in concentrations of monensin ranging from 1 X 10(-7) to 1 X 10(-6) M for durations up to 8 h. Electron microscopy revealed that the treated chondrocytes developed abnormal Golgi structures and a markedly distended rough endoplasmic reticulum. Biochemical and immunoassay studies showed that while total protein synthesis was only slightly impaired by monensin, the ionophore had pronounced effects upon the secretion of both type II collagen and proteoglycans. These two macromolecules responded to monensin inhibition in a similar fashion and accumulated within the affected chondrocytes. The kinetics of response over the monensin concentration range used was virtually identical for type II collagen and proteoglycan. Undersulfation of proteoglycan, caused by monensin, was examined by ion exchange chromatography and analysis of the products of chondroitinase ABC digestion. The results indicated that undersulfation affected all glycosaminoglycan chains in a general fashion rather than affecting a specific population of chains.
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PMID:Effects of the ionophore monensin on type II collagen and proteoglycan synthesis and secretion by cultured chondrocytes. 711 6

The subcellular localization of the enzymes involved in the glycosylation of proteoglycans was studied in rat ovarian granulosa cells by interfering with the normal traffic in the Golgi apparatus using brefeldin A. Cell cultures were metabolically labeled with [35S] sulfate and [3H]glucosamine, and the radiolabeled macromolecules were analyzed by ion-exchange and gel chromatography in combination with chondroitinase or heparitinase treatment. In the absence of brefeldin A, the cells synthesized both dermatan sulfate proteoglycans (DSPGs) and heparan sulfate proteoglycans (HSPGs) which were isolated from the culture medium, the plasma membrane, and intracellular compartments. However, in the presence of brefeldin A, the synthesized proteoglycans were almost exclusively HSPGs and were found only in the intracellular compartment. Analyses of HSPGs synthesized in the presence of brefeldin A indicated that: (i) the HS chains are synthesized on the same core protein as for the normal HSPGs, (ii) the chains are two to three times the normal molecular size; and (iii) a significant proportion of the HS chains are normally sulfated. Brefeldin A induces a disassembly of the proximal part of the Golgi complex, resulting in a redistribution of cis-, medial-, and trans-Golgi resident enzymes back to the endoplasmic reticulum (ER), and blocks the transport of proteins to the trans-Golgi network. Our results indicate that the complete set of enzymes involved in the biosynthesis of HS chains are localized in the ER/proximal part of the Golgi complex, whereas the enzymes involved in the elongation/sulfation of DS chains are exclusively located in the trans-Golgi network. Furthermore, our results indicate that the enzymes involved in the biosynthesis of HS chains are specific to HS core proteins, since no DS core proteins were substituted with HS chains in the presence of brefeldin A.
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PMID:Differential effect of brefeldin A on the biosynthesis of heparan sulfate and chondroitin/dermatan sulfate proteoglycans in rat ovarian granulosa cells in culture. 834 20

A monoclonal antibody was used in early studies to identify a novel chondroitin sulfate proteoglycan, secreted by L-2 cells, the core protein of which was approximately 100 kDa. To characterize this proteoglycan core protein at the molecular level, an L-2 cell cDNA library was probed by expression screening and solution hybridization. Northern blot analysis assigned transcript size to approximately 3.1 kilobases and, after contig assembly, the coding region of the mRNA corresponded to 2.18 kilobases. Immunoassays were performed to confirm the identity of this sequence, using a polyclonal antibody raised against an expressed fusion protein encoded by sequence representing the carboxyl half of the molecule. The antibody recognized the core protein in Western blots after prior digestion of the intact proteoglycan with chondroitinase ABC. Immunostaining tissue sections with the same antibody localized the proteoglycan to basement membranes, and expression of the entire sequence in Chinese hamster ovary K-1 cells showed that the protein encoded by the sequence secreted as a chondroitin sulfate proteoglycan. The core protein not only has motifs permitting glycosylation as a proteoglycan, but also possesses the endoplasmic reticulum retrieval signal, KDEL, which suggests that, in addition to its role as a basement membrane component, it may also participate in the secretory pathway of cells.
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PMID:Molecular characterization of a novel basement membrane-associated proteoglycan, leprecan. 1045 79

This study has used in situ hybridization, Northern blot analysis, and immunohistochemistry at the light and electron microscope levels to localize mRNAs and core proteins of biglycan in developing tibial epiphyseal cartilage of 10-day old Wistar rats. The expression of mRNAs and core proteins of biglycan appeared prominent in hypertrophic and degenerative chondrocytes associated with the epiphyseal ossification centre and the growth plate cartilage, but was not seen in the rest of epiphyseal cartilage. Northern blot analysis confirmed biglycan mRNA expression in the epiphyseal cartilage. Ultrastructural immunogold cytochemistry of the growth plate revealed that prominent immunolabelling was confined to the Golgi apparatus and cisternae of rough-surfaced endoplasmic reticulum of the hypertrophic and the degenerating chondrocytes, the early mineralized cartilage matrices of the longitudinal septum of the lower hypertrophic and the calcifying zones, and fully mineralized cartilage mitrices, which were present in the metaphyseal bone trabeculae. Furthermore, Western blot analysis of biglycan in extracts of fresh epiphyseal cartilage revealed that an EDTA extract, after chondroitinase ABC digestion, contains core proteins of biglycan, indicating the presence of biglycan in mineralized cartilage matrices. These results indicate that the distribution of biglycan is associated with cartilage matrix mineralization.
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PMID:Gene expression and immunohistochemical localization of biglycan in association with mineralization in the matrix of epiphyseal cartilage. 1084 12